1% Defining operator ?. It is a syntax sugar for marking variables: ?x
    2:-op(300, fy, ?).    3
    4lower_case_list(A,B) :-
    5	findall(Y,(member(X,A),lower_case(X,Y)),B).
    6
    7capitalize(WordLC, WordUC) :-
    8	atom_chars(WordLC, [FirstChLow|LWordLC]),
    9	atom_chars(FirstLow, [FirstChLow]),
   10	upcase_atom(FirstLow, FirstUpp),
   11	atom_chars(FirstUpp, [FirstChUpp]),
   12	atom_chars(WordUC, [FirstChUpp|LWordLC]),!.
   13
   14require_def(R)                                  --> ['(',':','requirements'], oneOrMore(require_key, R), [')'].
   15require_key(strips)				--> [':strips'].
   16require_key(typing)				--> [':typing'].
   17require_key('negative-preconditions')		--> [':negative-preconditions'].
   18require_key('disjunctive-preconditions')	--> [':disjunctive-preconditions'].
   19require_key(equality)				--> [':equality'].
   20require_key('existential-preconditions')	--> [':existential-preconditions'].
   21require_key('universal-preconditions')		--> [':universal-preconditions'].
   22require_key('quantified-preconditions')	        --> [':quantified-preconditions'].
   23require_key('conditional-effects')		--> [':conditional-effects'].
   24require_key(fluents)				--> [':fluents'].
   25require_key(adl)				--> [':adl'].
   26require_key('durative-actions')			--> [':durative-actions'].
   27require_key('derived-predicates')		--> [':derived-predicates'].
   28require_key('timed-initial-literals')		--> [':timed-initial-literals'].
   29require_key(preferences)			--> [':preferences'].
   30%require_key(constraints)			--> [':constraints'].
   31% Universal requirements
   32require_key(R)		--> [':', R].
   33
   34types_def(L)			--> ['(',':',types],      subsumptionList(L), [')'].
   35constants_def(L)		--> ['(',':',constants],  typed_list(name, L), [')'].
   36predicates_def(P)		--> ['(',':',predicates], oneOrMore(atomic_formula_skeleton, P), [')'].
   37
   38atomic_formula_skeleton(F)
   39                                --> ['('], predicate(P), typed_list(variable, L), [')'], {F =.. [P|L]}.

   42atomic_function_skeleton(f(S, L))
   43				--> ['('], function_symbol(S), typed_list(variable, L), [')'].
   44
   45functions_def(F)		--> ['(',':',functions], zeroOrMore(function_def,F), [')'].	%:fluents
   46
   47function_def(F)                 --> ['('],name(N),zeroOrMore(typed_arguments,A),[')'],{F = f(N,A)}.
   48typed_arguments(A)              --> oneOrMore(variable,Variables),['-'],name(T),{A = are(Variables,T)}.

constraints(C) --> ['(',':',constraints], con_GD(C), [')']. %:constraints

   52structure_def(A)		--> action_def(A).
   53structure_def(D)		--> durative_action_def(D).	%:durativeactions
   54structure_def(D)		--> derived_def(D).		%:derivedpredicates
   55
   56function_typed_list(W, [F|Ls])  --> oneOrMore(W, L), ['-'], !, function_type(T), function_typed_list(W, Ls), {F =.. [are,L,T]}.	%:typing
   57function_typed_list(W, L)	--> zeroOrMore(W, L).
   58
   59function_type(number)		--> [number].
   60emptyOr(_)			--> ['(',')'].
   61emptyOr(W)			--> W.
   62
   63% Actions definitons
   64action_def(action(S, L, Precon, Pos, Neg, Assign))
   65				--> ['(',':',action], action_symbol(S),
   66						[':',parameters,'('], typed_list(variable, L), [')'],
   67						action_def_body(Precon, Pos, Neg, Assign),
   68					[')'].
   69
   70durative_action_def(durativeAction(S, L, V, P1, P2))
   71                                --> ['(',':','durative-action'], action_symbol(S),
   72					[':',parameters,'('], typed_list(variable, L), [')'],
   73					[':',duration,'('], ['='], variable(_), value(V), [')'],
   74					durative_action_def_body(P1, P2), [')'].
   75
   76value(V)                        --> atomic_function(_,V).
   77value(V)                        --> f_exp(V).
   78
   79action_symbol(N)		--> name(N).
   80action_def_body(P, Pos, Neg, Assign)
   81				--> (([':',precondition], emptyOr(pre_GD(P)))	; []),
   82				    (([':',effect],       emptyOr(effect(Pos, Neg, Assign)))	; []).
   83
   84durative_action_def_body(P1, P2)
   85				--> (([':',condition], temp_GD(P1)) ; []),
   86				    (([':',effect], temp_GD(P2)) ; []).
   87
   88temp_GD(P)			--> ['(',and], oneOrMore(temp_GD,P), [')'].
   89temp_GD('at start'(P))          --> ['('],[at,start],pre_GD(P),[')'].
   90temp_GD('at end'(P))            --> ['('],[at,end],pre_GD(P),[')'].
   91temp_GD('over all'(P))          --> ['('],[over,all],pre_GD(P),[')'].
   92temp_GD(P)			--> pre_GD(P).
   93
   94pref_name(N)			--> name(N).
   95
   96atomic_function(_, F)		--> ['('], function_symbol(S), zeroOrMore(term, T), [')'], {F =.. [S|T]}.
   97
   98f_exp(N)			--> number(N).
   99f_exp(op(O, E1, E2))		--> ['('], binary_op(O), f_exp(E1), f_exp(E2), [')'].
  100f_exp('-'(E))			--> ['(','-'], f_exp(E), [')'].
  101f_exp(H)			--> f_head(H).
  102
  103binary_op(O)			--> multi_op(O).
  104binary_op('-')			--> ['−'].
  105binary_op('/')			--> ['/'].
  106multi_op('*')			--> ['*'].
  107multi_op('+')			--> ['+'].
  108multi_op('-')			--> ['-'].
  109
  110cond_effect(E)   		--> ['(',and], zeroOrMore(p_effect, E), [')'].				%:conditional-effects
  111cond_effect(E)			--> p_effect(E).						%:conditional-effects

  120effect(P, N, A)			--> ['(',and], c_effect(P, N, A), [')'].
  121effect(P, N, A)			--> c_effect(P, N, A).

  123c_effect(when(P, E))		--> ['(',when], gd(P), cond_effect(E), [')'].			%:conditional-effects
  124c_effect(P, N, A)		--> p_effect(P, N, A).
  125p_effect([], [], [])		--> [].
  126p_effect(Ps, Ns, [F|As])        --> ['('], assign_op(O), [')'], p_effect(Ps, Ns, As), {F =.. [O]}.

  128p_effect(Ps, [F|Ns], As)	--> ['(',not], atomic_formula(term,F), [')'], p_effect(Ps, Ns, As).
  129p_effect([F|Ps], Ns, As)	--> atomic_formula(term, F), p_effect(Ps, Ns, As).
  130p_effect(op(O, H, E))		--> ['('], assign_op(O), f_head(H), f_exp(E), [')'].	%:fluents , What is difference between rule 3 lines above???
  131
  132derived_def(derived(S,G))       --> ['(', ':', 'derived'], atomic_formula_skeleton(S), gd(G), [')'].
  133
  134:- ensure_loaded('sharedPDDL2.2').